Retaining means for pin used for rotor blade attachment



Sept. 29, 1959 R. s. THOMPSON RETAINING MEANS FOR PIN USED FOR ROTOR BLADE ATTACHMENT Filed May 28, 1957 INVENTOR. fill $0 S 490 PS0 BY UM;

RETAINING MEANS FOR PIN USED FOR ROTOR BLADE ATTACHlVIENT Ransom S. Thompson, East Hampton, Conn., assignor to the United States of America as represented by the Secretary of the Air Force Application May 28, 1957, Serial No. 662,306

5 Claims. (Cl. 253-77) This invention relates to a pin for securing a blade to a rotor of a rotary power conversion machine and, more particularly, to means for locking the pin, which secures a blade to a rotor, to the rotor.

It is well known to mount blades on a rotary power conversion machine such as a compressor or turbine by inserting a pin through the root of the blade and the rotor. This type of securing means prevents failure of the blades due to the bending stresses created therein, for example, by mechanical vibrations of the gearing. These pins, which secure the blades to the rotor, may become loose whereby the blade may no longer be connected to the rotor due to the pin failing to maintain its desired position. The present invention satisfactorily solves this problem by locking the pin to the rotor to retain the. pin in its desired position.

An object of this invention is to provide means for locking a pin, which secures the blade to the rotor, to the rotor.

Another object of this invention is to provide a pin, which secures the blade to the rotor, with an eccentric head for locking the pin to the rotor.

Other objects of this invention will be readily perceived from the following description.

This invention relates to a rotor having a groove in the periphery thereof in which the root portion of a blade is disposed. The blade is secured to the rotor by a pin extending through the root portion of the blade and the rotor. The pin has means to cooperate with retaining means on one face of the rotor to lock the pin to the rotor.

The attached drawing illustrates a preferred embodiment of the invention, in which Fig. 1 is an enlarged side elevational view of a portion of a rotor including the pin of the present invention; and

Fig. 2 is a sectional View taken along the line 22 of Fig. 1.

Referring to the drawing, there is shown a rotor 10, which is part of a rotary power conversion machine, such as a turbine or a compressor, rotating in the direction of the arrow 11. The rotor has a groove 12 in the periphery thereof in which a plurality of blades 14 is disposed. Each of the blades 14 has a root portion 15 disposed in the groove 12.

A pin 16 extends through openings in the walls of the rotor 10 and the root portion 15 of the blade 14 to secure the blade 14 to the rotor 10 to form a unitary assembly. The rotor 10 has an annular projection 17 on one face thereof including a downwardly extending lip 18, which is spaced from the face of the rotor 10 to form a circumferential groove 19 therebetween.

The pin 16 has an eccentric head 20 on one end thereof. The head 20 extends within the circumferential groove 19 Whenever the pin 16 is disposed in the position in which the pin secures the blade 14 to the rotor 10. The periphery or outer surface of the eccentric head 20 has a flat portion 21 and a curved portion 22. The fiat portion 21 extends from the center of the pin 16 a smaller nited States Patent 2,906,496 Patented Sept. 29, 1959 ice.

distance than the distance from the center of the pin to the lowermost portion of the lip 18 so that the head may be easily inserted within the circumferential groove 19. The curved portion has a varying radius from the center of the pin 16 in which the smallest radius, indicated by the arrow 24, is less than the distance from the center of the pin 16 to the base 23 of the circumferential groove 19. The curved portion 22 increases in radius from the center of the pin until its radius is substantially the same as the distance from the base 23 of the circumferential groove 19 to the center of the pin; this radius is indicated by the arrow 25. The curved portion 22 of the periphery of the head 20 continues to increase until its radius becomes greater than the distance from the base 23 of the groove 19 to the center of the pin; the maximum radius is indicated by the arrow 26. The end of the pin 16, which has the head 20 thereon, has a slot or recess 27 therein for the insertion of a screw driver or the like to rotate the pin 16.

In installing the pin 16 in the openings in the rotor 10 and the opening in the blade 14, the pin 16 is rotated by the insertion of a tool such as a screw driver in the slot or recess 27 to allow the flat portion 21 of the head 20 to pass beneath the lowermost portion of the lip 18. After the fiat portion 21 has passed beneath the lip 18, the pin 16 is rotated (clockwise in Fig. 1) until the curved portion 22 engages the base 23 of the circumfer: ential groove 19. This occurs substantially at the radius 25 of the curved portion 22 since this radius is substantially the same as the distance from the base of the groove 19 to the center of the pin 16. The friction forces between the periphery or outer surface of the head 20 and the base 23 of the circumferential groove 19 lock the pin 16 in the position shown in Fig. 1 when the rotor is not operating.

During rotation of the rotor, the effects of the centrifugal force on the head 20 not only hold the pin 16 in the position shown in Fig. 1, but also tend to rotate the head 20 into tighter engagement with the base 23 of the groove 19. Sudden starts and accelerations of the rotor in the direction indicated by the arrow 11 also tend to tighten the head 20 against the base 23 of the groove 19 in the locking direction. Thus, it is seen that there are no normal operating conditions of the rotor tending to unlock the head 20 of the pin 16 from its engagement with the base 23 of the groove 19. This is because the eccentric mass of the head 20 always tends to rotate the head 20in its locking direction when the direction of rotation of the rotor is as shown by the arrow 11. Whenever it is desired to remove the pin 16 to disconnect the blade 14 from the rotor 10, it is merely necessary to insert the screw driver or other tool in the slot 27 and rotate the pin 16 in a counterclockwise direction as shown in Fig. 1. When the head 20 has rotated to the position wherein the fiat portion 21 will pass beneath the lowermost portion of the lip 18, the pin is easily removed.

An advantage of this invention is that the pin, which secures the blade to the rotor, is retained in its locked position under all operating conditions of the rotor. Another advantage of this invention is that the pin, which secures the blade to the rotor, is not accidentally displaced.

For purposes of exemplification, a particular embodiment of the invention has been shown and described according to the best present understanding thereof. However, it will be apparent that changes and modifications in the arrangement and construction of the parts thereof may be resorted to without departing from the true spirit and scope of the invention.

I claim:

1. In combination, a rotor having a groove in the periphery thereof, a blade having a root portion disposed in the groove, a rotatably positioned pin extending through the root portion of the blade and the rotor to secure the blade to the rotor, the rotor having a lip on one face thereof extending radially inward and axially spaced from the face to form a circumferential groove between the lip and the one face, and the pin having an eccentric head thereon, the distance of the periphery of the head from the center of the pin varying from distances less than the distance of the radially innermost portion of the lip from the center of the pin to distances greater than the distance of the base of the circumferential groove from the center of the pin whereby the pin may be rotated and a portion of the head of the pin thus disposed within the circumferential groove of the rotor and locked to the rotor by the centrifugal forces created by rotation of the rotor.

2. In combination, a rotor having a groove in the periphery thereof, a blade having a root portion disposed in the groove, a rotatably mounted pin extending through the root portion of the blade and the rotor to secure the blade to the rotor, the rotor having a lip on one face thereof extending radially inward and axially spaced from the face to form a circumferential groove between the lip and the one face, the pin having a head thereon, the periphery of the head having a flat portion and a curved portion, the flat portion being less distance from the center of the pin than the radially innermost portion of the lip whereby the head of the pin may be rotated into a position such that it may be advanced into the circumferential groove, the curved portion of the head varying from a distance from the center of the pin less than the distance of the base of the circumferential groove from the center of the pin to a distance greater than the distance of the base of the circumferential groove from the center of the pin whereby the pin is locked to the rotor by centrifugal forces created by rotation of the rotor.

3. In combination, a rotor having a groove in the periphery thereof, a blade having a root portion disposed in the groove, a rotatably mounted pin extending through the root portion of the blade and the rotor to secure the blade to the rotor, the rotor having a lip on one face thereof extending radially inward and axially spaced from the face to form a circumferential groove between the lip and the one face, the pin having a head thereon, the periphery of the head having a portion at less distance from the center of the pin than the radially innermost portion of the lip whereby the pin may be rotated and a portion of the head of the pin thus disposed within the circumferential groove, a portion at substantially the same distance from the center of the pin as the base of the circumferential groove, and a portion at a greater distance from the center of the pin than the base of the circumferential groove whereby the pin is locked to the rotor by frictional engagement be- -l tween the base of the circumferential groove and one of the two last mentioned portions of the head.

4. In combination, a rotor incorporating a groove in the periphery thereof, a blade having a root portion disposed in the groove, and a rotatable pin for securing said blade to said rotor, said rotor having an annular projection incorporated on one face thereof including a depending lip portion extending radially inward and arranged in spaced relation relative to said one face to form a circumferential groove between said depending lip portion and said one face and said pin having an eccentric head having an outer surface, the distance of the periphery of the outer surface of said head from the center of the pin varying from distances less than the distance of the radially innermost portion of the lip portion from the center of the pin to distances greater than the distance of the base of the circumferential groove from the center of the pin whereby the pin may be rotated and a portion of the head thereby disposed within the circumferential groove and locked to the rotor by the centrifugal forces created by rotation of the rotor.

5. In combination, a rotor having a peripherally disposed groove, a blade having a root portion disposed in the peripherally disposed groove and a rotatable pin for securing the blade to the rotor, said rotor having a radially disposed lip formed on one face thereof and extending inward in spaced relation from the one face to form a circumferential groove between the lip and the face, said pin including a head on one end thereof, the periphery of the head having a fiat portion and a curved portion, the flat portion being less distance from the center of the pin than the radially innermost portion of the lip whereby the head of the pin may be rotated into a position such that it may be advanced into the circumferential groove, the curved portion of the head varying from a distance from the center of the pin less than the distance of the base of the circumferential groove from the center of the pin to a distance greater than the distance of the base of the circumferential groove from the center of the pin whereby the pin is locked to the rotor by centrifugal forces created by rotation of the rotor.

References Cited in the file of this patent UNITED STATES PATENTS 2,165,434 Wilson July 11, 1939 2,651,494 Persson Sept. 8, 19'53 FOREIGN PATENTS 724,281 Great Britain Feb. 16, 1955 745,073 Great Britain Feb. 22, 1956 749,279 Great Britain May 23, 1956 1,097,487 France Feb. 16, 1955 1,106,414 France July 20, 1955 1,136,390 France Dec. 29, 1956 

